App permissions are for phones. Here we're talking about PC.
Is it financially okay for most people to have two separate systems? Most would get a single laptop and be done with it.
Also, yes, one could use Linux/Unix, but that would take out a lot of commercial applications we may need (some simply do not have open source alternatives that are as good, or anywhere close) and take away the option of 90% of games made today.
Sure, I could download Linux, search and find open source alternatives for everything I can, and make do with inferior stuff if I sorely need something professional, and format every 3 months, keep away from gaming.
And would I find the computer enjoyable to use, or indeed, very usable?